Portuguese travelling to HK - Beijing - HK - London

Hi I'm Portuguese and I will be doing a multiple stop trip from London - Malaysia (no entry permit required); Malaysia - Bali (no entry permit required); Bali - Hong Kong (no entry permit required); Hong Kong - Beijing (less than 72 hours - Do I require an entry permit?); Beijing - Hong Kong (no entry permit required) and finally Hong Kong - London. I would like to know if I will require a visa for Beijing, of if I can just apply for the 72h free transit safely, and go and visit the Great Wall of China, as I've read in the website Passengers transiting in Beijing cannot leave the administrative area of the transit city- I am not sure if this includes visiting great wall or not.